Chronic granulomatous disease is a disorder that causes the immune system to malfunction, resulting in a form of immunodeficiency. Immunodeficiencies are conditions in which the immune system is not able to protect the body from foreign invaders such as bacteria and fungi. Individuals with chronic granulomatous disease may have recurrent bacterial and fungal infections. People with this condition may also have areas of inflammation (granulomas) in various tissues that can result in damage to those tissues. The features of chronic granulomatous disease usually first appear in childhood, although some individuals do not show symptoms until later in life.

Mutations in the CYBA, CYBB, NCF1, NCF2, or NCF4 gene can cause chronic granulomatous disease. There are five types of this condition that are distinguished by the gene that is involved. The proteins produced from the affected genes are parts (subunits) of an enzyme complex called NADPH oxidase, which plays an essential role in the immune system. Specifically, NADPH oxidase is primarily active in immune system cells called phagocytes. These cells catch and destroy foreign invaders such as bacteria and fungi. Within phagocytes, NADPH oxidase is involved in the production of a toxic molecule called superoxide. Superoxide is used to generate other toxic substances, which play a role in killing foreign invaders and preventing them from reproducing in the body and causing illness. NADPH oxidase is also thought to regulate the activity of immune cells called neutrophils. These cells play a role in adjusting the inflammatory response to optimize healing and reduce injury to the body.

Chronic granulomatous disease is estimated to occur in 1 in 200,000 to 250,000 people worldwide.

When chronic granulomatous disease is caused by mutations in the CYBB gene, the condition is inherited in an X-linked recessive pattern. The CYBB gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. Rarely, females with one altered copy of the CYBB gene have mild symptoms of chronic granulomatous disease, such as an increased frequency of bacterial or fungal infections.

Published Date: January 01, 2016
Published By: National Institutes of Health